AnaisHildegarde and SofiaHildegarde sound best to me - they're equally quirky-'European' as Hildegarde, but are glamorous and light-hearted enough to even out it's clunky factor. They sound like old-Hollywood stars or something.
These have a similar feel -

I'm definitely not psyched about Bethany Hildegarde. Together it's rather boring and doesn't match in style. I'd have to agree with previous posters that Hildegarde needs to be paired with something that has more spark, preferably something with a light and pretty sound.